This invention relates in some aspects to improvements to an apparatus for processing of data. The processing apparatus (or processor) may be ‘photonic’ in the sense that it uses optical, rather than electrical, signals in at least part of its processing. Such processors could be used, for example, for high speed, real time pattern matching; or may be adapted for a number of purposes such as feature detection, image recognition, and to perform a large number of mathematical or logic functions, approximations thereof and the like.
Optical processors which can for example be used in pattern recognition are known. For example, our WO2006/043057 describes a correlator apparatus that uses fast phase modulation and parallel optical processing to allow high speed correlation. Our WO2008/075021 describes another such system which uses amplitude modulation and intensity summing. Such processes can also be implemented in purely electronic systems. Examples of such systems are shown in our applications WO2007/068909 and WO2007/138258. All four of these documents are incorporated herein by reference.
Pattern recognition is concerned (in its broadest sense) with the process of recognising one or more known objects or sequences in incoming data, for example text imagery or DNA chains, by comparing known reference object(s) with the data:
There are many areas in which pattern recognition is used, from interrogating databases to locate specific search terms to biometric based recognition systems and target identification in two-dimensional imagery. Often the search is performed digitally using a suitably programmed processor to compare a known reference data string with the data to be searched to identify a match. One example is an internet search engine which compares one or more input reference words with internet data to identify a match.
When searching very large amounts of data, some pattern identification techniques may be slow or require very large amounts of processing power. Also when data is received at high data rates, for example at telecommunications data transfer rates, software based systems may be unable to perform pattern matching at this speed. In some cases, even special purpose electronic hardware may be impracticable or very difficult to implement due to considerations such as power consumption.